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Windows TCP/IP

CVE-2026-40401 — Windows TCP/IP Denial of Service Vulnerability

Important CVSS 7.1 EPSS 0.00331 2026-05 archive

Executive Summary

None

Overview

7.1
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
Exploitation Unlikely
MS Exploit Likelihood
Category Denial of Service
Released May 12 2026
Last Updated May 12 2026
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.00331 — 0.24691 percentile
NVD CVSS 7.1 HIGH — matches MSRC

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C
ATTACK VECTOR
Local
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
None
USER INTERACTION
None
SCOPE
Changed
CONFIDENTIALITY
None
INTEGRITY
None
AVAILABILITY
High
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 6.2

EPSS Score

0.00331
probability of exploitation in the next 30 days
0.24691 percentile - updated 2026-06-21
View on FIRST.org

Affected Products

17 affected products
Product KB Article Severity Impact Restart Required
Windows 10 Version 1607 for x64-based Systems 5087537 (Security Update) Important Denial of Service Yes
Windows 10 Version 1809 for x64-based Systems 5087538 (Security Update) Important Denial of Service Yes
Windows 10 Version 21H2 for x64-based Systems 5087544 (Security Update) Important Denial of Service Yes
Windows 10 Version 22H2 for x64-based Systems 5094127 (Security Update) Important Denial of Service Yes
Windows 11 Version 23H2 for ARM64-based Systems 5087420 (Security Update) Important Denial of Service Yes
Windows 11 Version 23H2 for x64-based Systems 5093998 (Security Update) Important Denial of Service Yes
Windows 11 Version 24H2 for ARM64-based Systems 5089549 (Security Update) 5089466 (Security Hotpatch Update) Important Denial of Service 5082063 Base: 7.1 Temporal: 6.2 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C 10.0.26100.8457 10.0.26100.8390 Yes None Windows 11 Version 24H2 for x64-based Systems 5089549 (Security Update) 5089466 (Security Hotpatch Update) Important Denial of Service 5082063 Base: 7.1 Temporal: 6.2 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C 10.0.26100.8457 10.0.26100.8390 Yes None Windows 11 Version 25H2 for ARM64-based Systems 5089549 (Security Update) 5089466 (Security Hotpatch Update) Important Denial of Service 5083769 Base: 7.1 Temporal: 6.2 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C 10.0.26200.8457 10.0.26200.8390 Yes None Windows 11 Version 25H2 for x64-based Systems 5089549 (Security Update) 5089466 (Security Hotpatch Update) Important Denial of Service 5083769 Base: 7.1 Temporal: 6.2 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C 10.0.26200.8457 10.0.26200.8390 Yes None Windows 11 Version 26H1 for ARM64-based Systems 5089548 (Security Update) Important Denial of Service Yes
Windows 11 version 26H1 for x64-based Systems 5089548 (Security Update) Important Denial of Service Yes
Windows Server 2012 5087470 (Monthly Rollup) Important Denial of Service Yes
Windows Server 2012 (Server Core installation) 5087470 (Monthly Rollup) Important Denial of Service Yes
Windows Server 2012 R2 5087471 (Monthly Rollup) Important Denial of Service Yes
Windows Server 2012 R2 (Server Core installation) 5087471 (Monthly Rollup) Important Denial of Service Yes
Windows Server 2016 5087537 (Security Update) Important Denial of Service Yes
Windows Server 2016 (Server Core installation) 5087537 (Security Update) Important Denial of Service Yes
Windows Server 2019 5087538 (Security Update) Important Denial of Service Yes
Windows Server 2019 (Server Core installation) 5087538 (Security Update) Important Denial of Service Yes
Windows Server 2022 5087545 (Security Update) 5087424 (Security Hotpatch Update) Important Denial of Service 5082142 Base: 7.1 Temporal: 6.2 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C 10.0.20348.5139 10.0.20348.5074 Yes None Windows Server 2022 (Server Core installation) 5087545 (Security Update) 5087424 (Security Hotpatch Update) Important Denial of Service 5082142 Base: 7.1 Temporal: 6.2 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C 10.0.20348.5139 10.0.20348.5074 Yes None Windows Server 2022, 23H2 Edition (Server Core installation) 5087541 (Security Update) Important Denial of Service Yes

Patches

10 patches
Article Type Restart
5087537 Security Update Yes
5087538 Security Update Yes
5087544 Security Update Yes
5094127 Security Update Yes
5087420 Security Update Yes
5093998 Security Update Yes
5089548 Security Update Yes
5087470 Monthly Rollup Yes
5087471 Monthly Rollup Yes
5087541 Security Update Yes

Known Exploits

Acknowledgments

Microsoft

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